UK scientists ask for licence to create human-cow embryo

Two teams of British scientists have applied for licences to create hybrid embryos from human and animal cells in order to create stem cells. The North East England Stem Cell Institute - a biotech research body run by the Universities of Durham and Newcastle - and the Stem Cell Laboratory based at Kings' College London have applied for three-year licences from the UK's Human Fertilisation and Embryology Authority (HFEA).

If granted, the licences would permit the teams to transfer human DNA into the oocytes of cows that have, in turn, had their nuclei removed. From this, embryos could be created that were 99.9 per cent human; the mitochondrial DNA being the only reproducible bovine remnant. The putative embryos would then be allowed to develop for six days, at which point pluripotent stem cells could be harvested. The licence would state - according to the law - that the nascent embryo must then be destroyed prior to 14 days gestation.

Stem cells are without peer in terms of therapeutic potential across medicine, with neurodegenerative disorders such as Parkinson's and Alzheimer's thought to hold the most imminent chance of a successful treatment. But their development has been slower than envisaged. The primary problem is that the human eggs required for the production of stem cells are in short supply and require an invasive operation to collect them. Kings' College lead researcher Dr Stephen Minger said that 'we are concerned that the current state of technology means that hundreds of eggs from young women are required to generate a single human embryonic stem cell line'. He added: 'Therefore we consider it more appropriate to use non-human eggs from live stock as a surrogate to generate these disease specific cell lines until the efficiency of the procedure is improved'.

The eventual aim of this field of research is to produce new tissue to replace defective tissue - from any organ - that is an exact genetic match for the patient: a form of personalised medicine. The hybrid stem cells would create a much wider pool of cells for scientists to work with and expedite their research. Researchers could perform a wide array of tests on the inexpensive and readily available hybrid cells before moving on to confirm their findings in the more expensive human eggs.

The Human Fertilisation and Embryology Act 1990 currently outlaws mixing human and animal eggs and sperm, but the legislation does not regulate nuclear transfer between human and animal cells. 'Part of the reason we are doing this is to get some sort of legal classification', said Dr Minger. A peer-reviewed panel of experts appointed by the HFEA are expected to take several months to make a decision on the licence application.